General Description Of Camera
Film and cameras that are all in one, commonly referred to as disposable single-use or one-time-use cameras, have become well known. The one-time-use camera is a simple point-and-shoot type camera comprising a conventional film cartridge loaded into a cartridge receiving chamber in a main body part, an unexposed film roll pre-wound from the film cartridge onto a film supply spool in a film supply chamber in the main body part, a film-exposing back-frame opening between the cartridge receiving and film supply chambers, a fixed-focus taking lens, a manually rotatable film winding thumbwheel coaxially engaged with a film winding spool inside the film cartridge for winding the filmstrip after each exposure, a metering lever for locking the thumbwheel, a single-blade shutter, a high energy lever for actuating the shutter blade to make an exposure and for moving the metering lever to unlock the thumbwheel, a manually depressible shutter release button for unlatching the high energy lever, a frame counter wheel that has a numerical scale of frame count indicia and is incrementally rotated to successively view the frame count indicia, a metering sprocket for incrementally rotating the frame counter wheel during film winding, a metering cam coaxially connected to the metering sprocket for controlling movement of the high energy lever and metering lever during film winding, an anti-backup pawl that engages the frame counter wheel to prevent its reverse rotation, a direct see-through viewfinder having front and rear viewfinder lenses, and in some models an electronic flash. A pair of separate front and rear cover parts house the main body part between them to complete the camera. The rear cover part connects to the main body part and/or to the front cover part to make the main body part light-tight. A decorative cardboard outer box or label at least partially covers the front and rear cover parts and has respective openings for the taking lens, etc.
To make an exposure on film, the shutter release button is manually depressed. This unlatches the high energy lever which is then pivoted via a high energy spring to impact against a strike tab on the shutter blade. The shutter blade in turn is pivoted open to uncover an exposure aperture. Once the high energy lever is pivoted beyond the strike tab, a return spring pivots the shutter blade closed to re-cover the exposure aperture.
The high energy spring continues to pivot the high energy lever as the shutter blade is being pivoted closed, in order to cause the high energy lever to pivot the metering lever out of locking engagement with the thumbwheel. The timing is such that once the shutter blade is pivoted closed the thumbwheel is freed to be manually rotated in the film winding direction. Rotation of the thumbwheel rotates the film winding spool inside the film cartridge to wind an exposed frame of the filmstrip from the back-frame opening into the film cartridge and to advance an unexposed frame of the filmstrip from the unexposed film roll to the back-frame opening. The rewinding movement of the filmstrip the equivalent of slightly more than one frame width rotates the metering sprocket in engagement with successive perforations in the filmstrip to incrementally rotate the frame counter wheel to view its next lower-numbered indicia. Also, the metering sprocket rotates the metering cam to return the high energy lever past the strike tab of the shutter blade and so that the high energy spring can hold the high energy lever re-latched. Since the high energy spring is then constrained, a metering spring (which is weaker than the high energy spring) is allowed to return the metering lever to locking re-engagement with the thumbwheel. Alternatively, when there is no metering spring as in U.S. Pat. No. 5,235,366 issued Aug. 10, 1993, the high energy spring returns the metering lever to locking engagement with the thumbwheel.
When the maximum number of frames available on the filmstrip have been exposed and the filmstrip is completely wound into the film cartridge, the one-time-use camera is given to a photofinisher who breaks away a cover door portion of the rear cover part from the main body part and removes the film cartridge with the exposed filmstrip from the cartridge receiving chamber. Then, he removes the exposed filmstrip from the film cartridge to develop the latent images and make prints for the customer.
Problem
U.S. Pat. No. 5,235,366 issued Aug. 10, 1993 and U.S. Pat. No. 6,033,133 issued Mar. 7, 2000 teach pivotably supporting the single-blade shutter using a fixed round pivot-support post that projects into an elongate pivot slot in the shutter blade. When the high energy lever is returned past the strike tab of the closed blade, to permit the high energy lever to be re-latched, the high energy lever presses against the strike tab. Ordinarily, the high energy lever might possibly be blocked by the strike tab. However, the elongate slot allows the high energy lever to shift or translate the shutter blade out of its way without pivoting the shutter blade open. This now is typical of many cameras having a single-blade shutter.
The issue becomes more complex when a dual blade shutter is used instead of a single-blade shutter. Generally, dual-blade shutters are center-opening, i.e. the two blades pivot open in opposite directions away from one other to uncover the exposure aperture and return to an overlapping closed relation to re-cover the exposure aperture. As in U.S. Pat. No. 5,136,324 issued Aug. 4, 1992, U.S. Pat. No. 5,258,797 issued Nov. 2, 1993, and U.S. Pat. No. 5,721,995 issued Feb. 24, 1998, individual fixed pivot-support posts project into respective round pivot holes in the two blades, and a rotatable or pivotable shutter driver for opening and closing the two blades projects into respective overlapping slots in the two blades. Movement of the shutter driver in one direction within the overlapping slots pivots the two blades about the pivot-support posts to open, and movement of the shutter driver in an opposite direction within the overlapping slots pivots the two blades about the pivot-support posts to close.